Gut and Brain: Investigating Physiological and Pathological Interactions Between Microbiota and Brain to Gain New Therapeutic Avenues for Brain Diseases

Abstract

Brain physiological functions or pathological dysfunctions do surely depend on the activity of both neuronal and non-neuronal populations. Nevertheless, over the last decades, compelling and fast accumulating evidence showed that the brain is not alone. Indeed, the so-called “gut brain,” composed of the microbial populations living in the gut, forms a symbiotic superorganism weighing as the human brain and strongly communicating with the latter via the gut–brain axis. The gut brain does exert a control on brain (dys)functions and it will eventually become a promising valuable therapeutic target for a number of brain pathologies. In the present review, we will first describe the role of gut microbiota in normal brain physiology from neurodevelopment till adulthood, and thereafter we will discuss evidence from the literature showing how gut microbiota alterations are a signature in a number of brain pathologies ranging from neurodevelopmental to neurodegenerative disorders, and how pre/probiotic supplement interventions aimed to correct the altered dysbiosis in pathological conditions may represent a valuable future therapeutic strategy.

The Impact of Probiotic Bacillus subtilis on Injurious Behavior in Laying Hens

“…In addition, probiotics have successfully attenuated anxiety and depressive behaviors in rat offspring separated from their mother [ 158 , 159 ] and the obsessive-compulsive-like behaviors in mice [ 160 , 161 ]. These results support the psychobiotics theory [ 15 , 162 ] (i.e., a special class of probiotics (beneficial bacteria) delivering mental and cognitive health benefits (such as anxiolytic and antidepressant effects) to individuals) and provide a potential to use probiotics as a biotherapeutic strategy for improving a host’s mental and cognitive function in humans and other animals including chickens [ 163 , 164 , 165 , 166 , 167 , 168 , 169 , 170 ]. Probiotics may have similar effects on chicken behavior due to the human–animal transmission occurs during the evolution and ecology of gastrointestinal microbial development (the host–microbial coevolution) [ 171 , 172 ].…”

Fecal Microbiota Transplantation as New Therapeutic Avenue for Human Diseases

“…Gut microbiota surely plays a role in brain functions and dysfunctions [ 229 ]. In order to rebalance the gut microbiota in brain diseases, probiotics and prebiotics reported potential [ 17 ], but FMT has the greater advantage of transferring eh entire microflora.…”

“…Different strategies exist to modulate an altered dysbiotic gut microbiota composition aiming at a more physiological profile. These therapies can either (i) target/eliminate specific pathogenic strains using antibiotics (“ antimicrobial therapy ”) or phage (“ page therapy ”), or (ii) administrate specific live microbe (in the form of “ probiotics ”) or (iii) transfer entire microbiota communities (“ fecal microbiota transplantation ”) [ 17 ]. A ntimicrobial therapy was the first that came into place and it aimed to directly target the microbes that necessitated being controlled/restricted by means of antibiotics.…”

“…Beyond the antimicrobial and phage therapies, it is also possible to regulate gut microbiota composition utilizing the administration of specific living bacteria in the form of probiotics . Probiotics are administered as a supplement and have shown to have enormous beneficial effects on a wide range of gastrointestinal diseases and brain pathologies [ 17 , 25 ]. However, probiotics still come with limitations.…”

Dynamic and Systemic Perspective in Autism Spectrum Disorders: A Change of Gaze in Research Opens to A New Landscape of Needs and Solutions

“…Accumulating evidence reveals the multifaceted features of the disturbances of the MGB-axis in the pathophysiology of brain disorders and its potential mechanisms [ 108 ]. According to this perspective, the numerous factors that can influence the microbiota in the First 1000 Days (i.e., maternal microbiota, mode of delivery, breastfeeding, nutrition, infections and early antibiotic therapies) should be considered crucial risk/health factors for neurodevelopment [ 14 , 109 , 110 ].…”